Related Experiment Videos
Moraxella bovis hemolysin
Abstract:
Moraxella bovis hemolysin was readily filterable through polycarbonate membrane filters, but not through nitrocellulose filters. The hemolysin was filterable through polycarbonate filters with pore diameters of greater than or equal to 0.015 micron (APD). Of the hemolytic activity of cell-free filtrates, 74% could be pelleted by ultracentrifugation at 100,000 X g for 2 1/2 hours. Hemolytic activity could be demonstrated in preparations of outer membrane fragments isolated from log-phase cultures. Hemolysin in M bovis broth cultures reached a maximum concentration in late logarithmic phase (4.5 hours after inoculation) and declined thereafter. Hemolysin was inactivated by heat, trypsin, formalin, and lyophilization.
Insights
Moraxella bovis hemolysin, a key virulence factor, is filterable and associated with outer membrane fragments. Its concentration peaks during late growth phases and it is inactivated by various treatments.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Moraxella bovis is an important bovine pathogen.
- Hemolysins are critical virulence factors in bacterial infections.
- Understanding M. bovis hemolysin properties is crucial for developing control strategies.
Purpose of the Study:
- To characterize the physical and biochemical properties of Moraxella bovis hemolysin.
- To determine the cellular location and optimal production phase of the hemolysin.
- To investigate the stability and inactivation methods for M. bovis hemolysin.
Main Methods:
- Filtration studies using polycarbonate and nitrocellulose membranes with defined pore sizes.
- Ultracentrifugation to pellet hemolytic activity from cell-free filtrates.
- Isolation and analysis of outer membrane fragments from bacterial cultures.
- Growth curve analysis to correlate hemolysin production with bacterial growth phase.
- Inactivation assays using heat, trypsin, formalin, and lyophilization.
Main Results:
- Moraxella bovis hemolysin passed through polycarbonate filters (≥0.015 micron APD) but not nitrocellulose filters.
- Ultracentrifugation pelleted 74% of hemolytic activity from cell-free filtrates.
- Hemolytic activity was detected in isolated outer membrane fragments.
- Maximum hemolysin concentration occurred at 4.5 hours (late logarithmic phase) and decreased subsequently.
- Hemolysin was inactivated by heat, trypsin, formalin, and lyophilization.
Conclusions:
- Moraxella bovis hemolysin is a filterable molecule, likely associated with outer membrane components.
- Hemolysin production is growth-phase dependent, peaking in late logarithmic phase.
- The hemolysin exhibits sensitivity to heat, enzymatic, chemical, and freeze-drying inactivation methods.